We discuss the sensitivity of the $e^+ e^- rightarrow W^+ W^-$ cross section at a future $e^+ e^-$ collider with $sqrt{s}=500$GeV to the non-decoupling effects of a techni-$rho$ like vector resonance. The non-decoupling effects are parametrized by th
e chiral coefficients of the electroweak chiral perturbation theory. We define renormalization scale independent chiral coefficients by subtracting the Standard Model loop contributions. We also estimate the size of the decoupling effects of the techni-$rho$ resonance by using a phenomenological Lagrangian including the vector resonance.
